Salivary Thiocyanate as a Biomarker of Cystic Fibrosis Transmembrane Regulator Function.

Improved methods are needed to reliably assess Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) function in vivo in light of recent therapeutic developments targeting the CFTR protein. Oral fluid from patients with cystic fibrosis (CF) and healthy controls (HCs) were studied using colorimetry and nonresonant Raman spectroscopy. Colorimetry experiments showed only a 36% decrease in thiocyanate (SCN-) concentration, but a sharp Raman peak at 2068 cm-1, attributable to (SCN-) vibrations, normalized to C-H peak, was on average 18 times higher for HC samples. Samples from patients undergoing treatment with CFTR modulators including ivacaftor, lumacaftor, and tezacaftor showed a high normalized peak in response to therapy. The peak intensity was consistent in longitudinal samples from single donors and in stored samples. The Raman peak ratio is a more sensitive, convenient, noninvasive biomarker for assessments of the therapeutic efficacy of drugs targeting CFTR and provides a value that is in much better agreement with theoretical expectations of saliva SCN- concentrations compared to colorimetry. This insight may greatly facilitate assessments of CFTR modulator efficacy in individual patients.

Lung clearance index is sensitive to small airway disease in pediatric lung transplant recipients.

BACKGROUND: The principal obstacle to long-term survival after lung transplant is chronic lung allograft dysfunction (CLAD), which primarily affects the small airways. After transplant, patients are monitored with spirometry, which is a generally insensitive detector of small airways obstruction. The lung clearance index (LCI) is a measure obtained during multiple breath washout (MBW) maneuvers. We hypothesized that among lung allograft recipients, LCI would detect small airways disease not detected with spirometry. METHODS: This study enrolled 15 patients, 5 of whom already had a diagnosis of CLAD. We added MBW as an additional index of peripheral airway function to the established post-transplant routine care protocol. RESULTS: Of trials, 87.9% yielded valid measurements, and single maneuvers were 2-8 minutes. LCI did not yield any false-negative findings-no patients were considered obstructed by forced expiratory volume in 1 second (FEV1) but normal by LCI. At enrollment, 6 patients without CLAD had an elevated LCI, and 4 progressed to CLAD. Only 2 of these 4 patients would have been identified by a decrease in FEV1. CONCLUSIONS: LCI identified lung allograft dysfunction in more patients than the use of standardized spirometric measures, including patients with abnormal FEV1. These data suggest that LCI from MBW may be a more sensitive means to detect allograft peripheral airway disease than standard methods for measurement of small airways function.

Novel CFTR variants identified during the first 3 years of cystic fibrosis newborn screening in California.

California uses a unique method to screen newborns for cystic fibrosis (CF) that includes gene scanning and DNA sequencing after only one California-40 cystic fibrosis transmembrane conductance regulator (CFTR) panel mutation has been identified in hypertrypsinogenemic specimens. Newborns found by sequencing to have one or more additional mutations or variants (including novel variants) in the CFTR gene are systematically followed, allowing for prospective assessment of the pathogenic potential of these variants. During the first 3 years of screening, 55 novel variants were identified. Six of these novel variants were discovered in five screen-negative participants and three were identified in multiple unrelated participants. Ten novel variants (c.2554_2555insT, p.F1107L, c.-152G>C, p.L323P, p.L32M, c.2883_2886dupGTCA, c.2349_2350insT, p.K114del, c.-602A>T, and c.2822delT) were associated with a CF phenotype (42% of participants were diagnosed at 4 to 25 months of age), whereas 26 were associated with CFTR-related metabolic syndrome to date. Associations with the remaining novel variants were confounded by the presence of other diseases or other mutations in cis or by inadequate follow-up. These findings have implications for how CF newborn screening and follow-up is conducted and will help guide which genotypes should, and which should not, be considered screen positive for CF in California and elsewhere.

Longitudinal assessment of lung function from infancy to childhood in patients with cystic fibrosis.

RATIONALE: Infant pulmonary function testing (IPFT) has become an important clinical tool for the evaluation of lung function in infants with Cystic Fibrosis (CF); however, it is still unclear whether lung function in infancy is predictive of lung function later in life. We hypothesized that measures of airflow obstruction by IPFT would correlate strongly with lung function by conventional spirometry later in childhood. STUDY DESIGN AND METHODOLOGY: A retrospective analysis was performed of all CF infants studied with IPFT at the University of Minnesota Children's Hospital between September 1994 and March 2003. A total of 41 patients underwent IPFT and had valid spirometry results available at age 6 or later. IPFT values, such as I:E ratio, respiratory rate, tidal volume, and T(ptef)/T(e), were calculated from tidal breathing loops. Passive respiratory system mechanics, which included C(rs), R(rs), and tau(rs), were measured by the single breath end-inspiratory occlusion technique. Forced expiratory flows, including V(max)FRC, FVC, FEF(50), and FEF(75), were obtained by rapid thoracic compression and included a full vital capacity maneuver by the multiple inflation method. FRC measurements were calculated from data obtained via nitrogen washout in a subset of patients. In addition, information on age at diagnosis and results of oropharyngeal (OP) cultures at diagnosis and on subsequent visits was recorded. Standard spirometry was performed in all patients starting at age 5. The first valid flow-volume loop after age six was selected for analysis. RESULTS: Significant correlations were observed for the R(rs) and the FEF(50) by IPFT and the FEV(1) and the FEF(25-75) by standard spirometry (r > 0.4 and P < 0.03 for all correlations). These correlations were the strongest for those IPFT measurements obtained within 1 month of diagnosis and when R(rs) was expressed as sG(rs). The correlations observed were independent of the effects of age at diagnosis, gender and presence of Pseudomonas in oropharyngeal cultures at the time of diagnosis. Mean R(rs) declined from 0.050 to 0.027 cm H(2)O/ml/sec with treatment (P < 0.0001). There were no other significant associations found between other IPFT values measured and FEV(1) by spirometry. CONCLUSIONS: Measures of airflow obstruction on IPFT, specifically R(rs), sG(rs), and FEF(50), were strongly correlated with future lung function. IPFT measurement of R(rs) in addition to forced expiratory flows may help select patients at the greatest risk of early lung function decline. This study supports the use of R(rs) as a surrogate variable to help assess the impact of early therapies in CF.

Steroid-sparing effect of omalizumab for allergic bronchopulmonary aspergillosis and cystic fibrosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a complication commonly encountered in patients with CF that produces significant respiratory morbidity. Chronic airway colonization with Aspergillus induces strong inflammatory responses with high IgE levels. Current guidelines for therapy include prolonged courses of systemic corticosteroids as the main therapeutic strategy. However this has the potential to induce significant detrimental side effects in children. Omalizumab is a humanized monoclonal antibody directed against IgE that prevents its binding to high- and low-affinity receptors on effector cells. It has been shown to be effective in improving asthma control in patients with a strong allergic component. We present our long term experience with the use of Anti-IgE therapy in three children with CF and ABPA (mean age at start of therapy 14.2 years) who were steroid dependent. All three were already experiencing significant side effects from chronic steroid therapy. After the start of Omalizumab these children have experienced significant and sustained clinical improvements at the same time that they were discontinued from chronic systemic steroids. Our experience suggests that IgE blockade has tremendous potential as a strategy to control this disease in steroid dependent patients.